High-efficient and recoverable Mo72V30@Fe3O4/C catalyst for oxidation of hydroxyfurfural

It is a great challenge to develop recyclable polyoxometalate (POM) based catalysts with high efficiency and selectivity in oxidation of 5-hydroxymethylfurfural (HMF). In this paper, MIL-88A(Fe) derived Fe3O4/C is designed as an efficient carrier to entrap Keplerate-type POM and form Mo72V30@Fe3O4/C composite catalyst. Due to the confined and synergistic effect of Fe3O4/C framework, as compared to other reported catalysts, Mo72V30@Fe3O4/C exhibits the highest catalytic activity and selectivity in aerobic oxidation of HMF with a 99.4 % conversion and a 100 % selectivity to 2,5-diformylfuran (DFF). The Mo72V30@Fe3O4/C catalyst still shows a high activity even after ten cycles. A possible synergistic catalytic mechanism is proposed that Mo72V30@Fe3O4/C oxidizes HMF to DFF through a proton coupled electron transfer (PCET) process indicating the polymetallic center in Mo72V30@Fe3O4/C synergistically promotes this reaction. This work not only provides a giant POM based catalyst in biomass conversion, but also highlights a polymetallic active center concept for the design of biomass oxidation catalyst.